Notch-finding mechanism and method of using the same

ABSTRACT

One embodiment of the invention is a notch finding mechanism that at least partially supports and drives a core carrying printer media. The notch finding mechanism includes a notch finding spring and a plurality of support posts that extend from a support disk. The notch finding spring includes a plurality of fingers constructed of a flexible sheet material, and the fingers are positioned circumferentially and adjacent each other to define a plurality of spaces between the fingers. In addition, the fingers are biased radially outwardly, and each of the fingers has a free end that has a width that is approximately matched to a width of a notch in an end of the core. The bias of one of the fingers urges the free end of the finger into the notch aligned with the finger when the core is placed over the fingers and is rotated a small amount.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.60/719,411, filed Sep. 21, 2005, which is hereby incorporated herein inits entirety by reference.

FIELD OF INVENTION

The present invention involves a notch finding mechanism for coupling adrive assembly to a hollow cylindrical core and, more particularly, theuse of a notch finding mechanism to couple a printer media roll to adrive assembly.

BACKGROUND OF THE INVENTION

Hollow cylindrical cores are used in the printing industry to carryrolls of printer media, such as paper, labels, or ink ribbon. The corescan be driven to rotate in a forward or backward direction by coupling adrive assembly to the core. One method of coupling a drive assembly to acore includes engaging keys on a drive disk into notches in the end ofthe core. More specifically, in the example shown in FIG. 1, the drivedisk 10 extends in a radially outward direction from the drive shaft 12,and extending past the periphery of the drive disk 10 in a radiallyoutward direction are the one or more keys 14, or protrusions. In theexample shown in FIGS. 2A and 2B, the hollow cylindrical core 20includes one or more notches 22 at an end 23 of the core 20 that extendfrom an inner diameter 24 of the core 20 towards an outer diameter 25 ofthe core 20. To load the core 20 onto the keyed disk 10 described above,an operator rotates the core 20 until the notches 22 at the end 23 ofthe core 20 align with the keys 14. The keys 14 are then engaged intothe notches 22 in the core 20, allowing the transfer of rotation of theshaft 12 to the core 20.

This loading operation can be cumbersome for the operator, especiallywhen the core 20 is carrying a large printer media roll. In addition,the core 20 can slip away from the disk 10, causing the keys 14 todisengage from the notches 22 and the media to misfeed and jam theprinter.

Therefore, a need in the art exists for a device that radially couples acore onto a drive shaft to transmit the rotational energy from the driveshaft to the core.

BRIEF SUMMARY OF THE INVENTION

According to various embodiments, a notch finding mechanism is providedfor at least partially supporting and driving a core of a printer mediasupply. The core defines at least one notch at an end of the core, andthe notch finding mechanism includes a drive shaft and a notch findingspring. The notch finding spring is driven by the drive shaft andincludes a plurality of fingers positioned circumferentially about acentral axis and adjacent to each other. Each finger is biased in aradially outward direction and has a free end. The bias of the fingersurges the free end of one of the fingers into the notch defined in theend of the core when the core is placed over the plurality of fingersand rotated.

In another embodiment, a notch finding spring is provided for at leastpartially supporting and driving a core of a printer media supply. Thecore defines at least one notch at an end of the core, and the notchfinding spring includes a plurality of fingers. The fingers arepositioned circumferentially about a central axis and adjacent eachother, are biased in a radially outward direction, and each have a freeend. The bias of the fingers urges the free end of one of the fingersinto the notch defined in the end of the core when the core is placedover the plurality of fingers and rotated.

According to another embodiment, a method of supporting and driving acore of a printer media supply is provided. The method includes thesteps of: (1) positioning the core over a notch finding spring that hasa plurality of fingers with a radially outward bias, and (2) rotatingthe core and the notch finding spring relative to each other a smallamount until one of the fingers biases into a notch defined in the core.

In yet another embodiment, a notch finding spring is provided fordriving a core that defines at least one notch adjacent to an end of thecore. The notch finding spring includes a plurality of fingers that arepositioned circumferentially about a central axis and adjacent to eachother, are biased in a radial direction, and have a free end. The freeend includes an engaging portion, and the bias of the fingers urges theengaging portion of one of the fingers into the notch when the core isplaced adjacent to the plurality of fingers and rotated.

In another embodiment, a notch finding spring is provided for driving acore. The notch finding spring is secured to the core and includes aplurality of fingers that are positioned circumferentially about acentral axis and adjacent to each other. In addition, each finger isbiased in a radial direction and includes a free end, and the free endincludes an engaging portion that, because of the bias of each finger,is urged into a notch defined adjacent to an end of a drive shaft whenthe drive shaft is placed adjacent to the plurality of fingers andrelatively rotated a small amount.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 is an end view of a prior art coupling mechanism;

FIG. 2A is a side view of a hollow cylindrical core having a notchedend;

FIG. 2B is an end view of the notched end of the hollow cylindrical coreof FIG. 2A;

FIG. 3 is a plan view of a printer and a notch finding mechanismaccording to one embodiment of the invention;

FIG. 4A is a perspective view of a notch finding mechanism and clutchassembly according to one embodiment of the invention;

FIG. 4B is a side view of the notch finding mechanism and clutchassembly of FIG. 4A;

FIG. 5 is an exploded view of the notch finding mechanism and clutchassembly of FIG. 4A;

FIG. 6 is a perspective view of the notch finding mechanism and clutchassembly of FIG. 4A coupled to a hollow cylindrical core;

FIG. 7 is a side view of a finger of the notch finding spring of FIG.4A;

FIG. 8 is a perspective view of a core mounted onto the notch findingmechanism of FIG. 4A;

FIG. 9 is a top view of the notch finding spring of FIG. 4A;

FIG. 10 is an exemplary dimensional specification for the notch findingspring of FIG. 4A;

FIG. 11 is a partial plan view of a cut detail for the notch findingspring of FIG. 10;

FIG. 12 is a cross sectional view of an exemplary dimensionalspecification for a finger of the notch finding spring of FIG. 4A;

FIG. 13 is a cross sectional view of the notch finding mechanism andclutch assembly of FIG. 4A;

FIG. 14 is a perspective view of a notch finding spring according toanother embodiment of the invention;

FIG. 15 is a perspective view of the notch finding spring of FIG. 14coupled with a hollow cylindrical core;

FIG. 16A is a plan view of an exemplary cut detail for the notch findingspring of FIG. 14;

FIG. 16B is a partial plan view of the cut detail of FIG. 16A;

FIG. 17A is a side view of a notch finding spring according to anotherembodiment of the present invention;

FIG. 17B is a plan view of the notch finding spring of FIG. 17A;

FIG. 18 is a side view of notch finding spring according to oneembodiment of the invention;

FIG. 19 is a side view of a notch finding spring according to oneembodiment of the invention;

FIG. 20 is a side view of a notch finding spring according to oneembodiment of the invention;

FIG. 21 is a side view of a notch finding spring according to oneembodiment of the invention;

FIG. 22 is a side view of a notch finding spring according to oneembodiment of the invention;

FIG. 23 is a side view of a notch finding spring according to oneembodiment of the invention;

FIG. 24 is a perspective view of a notch finding spring according to oneembodiment of the invention; FIG. 25 is a side view of a finger of anotch finding spring according to one embodiment of the invention;

FIG. 26 is a side view of a finger of a notch finding spring accordingto one embodiment of the invention;

FIG. 27 is a side view of a finger of a notch finding spring accordingto one embodiment of the invention;

FIG. 28 is a side view of a finger of a notch finding spring accordingto one embodiment of the invention; and

FIG. 29 is a side view of a notch finding spring according to oneembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the present invention address one or more of theabove needs and achieve other advantages by providing a notch findingmechanism for radially coupling the rotation of a drive shaft to ahollow cylindrical core. For example, certain embodiments of the notchfinding mechanism include a notch finding spring mounted to an end ofthe drive shaft and having a plurality of fingers that are radiallyoutwardly biased so as to seat within a notch defined in the mediasupply core with a relatively small amount of rotation between thespring and the core. This is enabled by the large number of fingers,such as twelve fingers, that are circumferentially positioned andconfigured to insert as a group into the core. And, in variousembodiments, the outward bias of the fingers allows them toautomatically seat in the notch or notches of the core, enablingsingle-handed loading of the core without attention or regard to therelative rotational position between the drive shaft and the core.

In one embodiment, the present invention includes a notch finding springfor at least partially supporting and driving a core of a printer mediasupply. The core defines at least one notch at its end. Included in thenotch finding spring are a plurality of fingers that arecircumferentially positioned adjacent to each other. Further, thefingers are biased in a radially outward direction, and each of thefingers includes a free end that can move radially at least a smallamount. The bias of at least one of the fingers urges its free end intothe notch defined in the end of the core when the core is placed overthe plurality of fingers and relatively rotated (i.e., the core isrotated, the spring is rotated, or both) a small amount, such as 45°,30° or less.

In addition, each of the fingers is constructed of a flexible sheetmaterial. For example, the sheet material fingers may extend from afixed end in a first axial direction, allowing their insertion into thecore. Each of the fingers may also have an arcuate shaped profile thatis defined by the fingers extending in a first direction from the fixedend, bending in a radially outward direction through an arc portion andextending in a second axial direction generally opposite the first axialdirection toward the free end.

In another aspect, each of the fingers has a width matched approximatelyto that of the notch for a firm fit. Also, a first diameter of aroundthe free ends of the fingers is greater than an inside diameter of thesupply core, and a second diameter around the arc portion is less thanthe inside diameter of the supply core. This allows easy placement ofthe second diameter into the core and urging of the free ends at thefirst diameter into the notch.

Each of the fingers may have a varying width, being tapered at the freeend for insertion into the notch, thicker at a middle portion andtapered near the arc portion. The taper near the arc portion promotesthe insertion of several rigid support posts supported by the driveshaft between the fingers. These support posts provide torsionalstability for the spring and radial support for reasonable centering ofthe rotational axis of the core independently of the flexing of thespring fingers.

Various embodiments of the present invention provide several advantages.For example, the notch finding spring maybe easily manufactured bypunching and drawing from a flexible sheet material, such as stainlesssteel or beryllium copper. As another example, the notch finding springcan be used with existing clutch and drive assemblies by sizing thewidth of the fingers to approximately match the width of the notches inexisting cores. Further, the bias of the fingers and spacing of thefingers close together allows for single-handed loading of the core ontothe notch finding spring without regard to relative rotational position.In addition, movement of the core in the axial direction is prevented orrestricted as a result of the bias of the fingers in a radially outwarddirection against the inner diameter of the core.

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which some, but not allembodiments of the invention are shown. Indeed, the invention may beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will satisfy applicable legalrequirements. Like numbers refer to like elements throughout.

Printer and Drive Assembly

As shown in FIG. 3, the printer 30 includes a rectangular housing 31.The housing 31 includes a base 33 and a lid or cover (not shown). Thebase 33 has a rectangular shape with a wall structure that extendsupwardly from the base 33 to support and contain various electronic andmechanical assemblies of the printer 30.

The base 33 of the housing 31 supports a print head assembly 40, a driveassembly 50, and a clutch assembly 60. The print head assembly 40includes a platen roller 41, a print head 42, and media guide surfaces43. The print head assembly 40 urges a printer media 80 between theplaten roller 41 and the print head 42 to allow the print head 42 toprint on the printer media 80.

The drive assembly 50 includes a drive motor 51 that rotates a driveshaft 52. The drive motor can include, for example, a stepper motor. Thedrive shaft 52 has a driven end 53 adjacent to the drive motor 51 and afree end 54 opposite the driven end 53. The drive shaft 52 furtherincludes a drive disk 55 that extends in a radially outward directionfrom the axis of rotation of the drive shaft 52 and is positioned on thedrive shaft 52 near the free end 54. The drive assembly 50 furtherincludes a support pin 56 that is positioned opposite the drive shaft52. A non-driven end of the hollow cylindrical core is rotatably mountedon and vertically supported by the support pin 56, which may or may notbe keyed.

The clutch assembly 60 engages to transmit the rotational energy fromthe drive shaft 52 and disengages when the torque on the drive shaft 52at the clutch assembly 60 exceeds a particular amount. As shown in FIGS.4A and 4B, the clutch assembly 60 includes the drive disk 55, a supportdisk 61, and a first, second, and third intermediate frictional disks201, 202, 203, which are shown in FIG. 5. The drive disk 55 isintegrally attached to the drive shaft 52 and extends in a radiallyoutward direction from the drive shaft 52. The support disk 61 isseparate from the drive shaft 52 and includes a central aperture 63 forreceiving the end 54 of the drive shaft 52 and a mounting surface 64 formounting adjacent to the drive disk 55. Between the support disk 61 andthe drive disk 55 are the intermediate frictional disks 201, 202, 203that have frictional material on both sides and frictionally engage eachother to couple the support disk 61 to the drive disk 55 with a designed“torque versus rotational” slip behavior.

The first intermediate frictional disk 201 is coupled to the drive disk55, and the second intermediate frictional disk 202 is coupled to thesupport disk 61. The third intermediate frictional disk 203 ispositioned between the first 201 and second intermediate frictionaldisks 202 and frictionally engages the first 201 and second intermediatefrictional disks 202. In one embodiment, the intermediate frictionaldisks 201, 202 are made of cartridge brass, the support disk 61 is madeof an unfilled polycarbonate, and the drive disk 55 and drive shaft 52are made of injection molded nylon 6/6.

To couple the intermediate frictional disks 201, 202 to the drive disk55 and the support disk 61, the drive disk 55 and the support disk 61include one or more keys 210 that protrude axially from the matingsurfaces of each disk 55, 61 and extend lengthwise in a radially outwarddirection from the center of each disk 55, 61, as shown in FIG. 5. Thekeys are positioned towards the center of the drive disk 55 and thesupport disk 61. Each of the intermediate frictional disks 201, 202include a central aperture 215 which is adapted for receiving the end ofthe drive shaft 52, and one or more notches 216 that extend in aradially outward direction from the central aperture 215. The notches216 receive the keys 210 on the support disk 61 and drive disk 55, whichcouples the drive disk 55 to the first intermediate frictional disk 201and the support disk 61 to the second intermediate frictional disk 202.The keys 210 and notches 216 are not limited to being positioned in thecenter of the disks 201, 202, 55, and 61 and could be positioned, forexample, along the periphery of the disks 201, 202, 55, and 61.

When the torque on the drive shaft 52 at the clutch assembly 60 is belowa particular amount, intermediate frictional disks 201, 202 engage thethird intermediate frictional disk 203, and the rotational energy of thedrive shaft 52 is transferred to the support disk 61. If the torque onthe drive shaft 52 at the clutch assembly 60 exceeds the particularamount, the intermediate frictional disks 201, 202 disengage from thethird intermediate frictional disk 203, allowing the drive disk 55 torotate independently of the support disk 61.

The printer described above is for illustration purposes only. It isenvisioned that one of skill in the art would understand that thepresent invention is suitable for use in a variety of types of printers,such as thermal head printers, portable printers, or thermal transferprinters, or even other driven media or core driven devices, such asfilm rolls or paper rolls.

Notch Finding Mechanism

A notch finding mechanism 100 of one embodiment of the present inventioncouples a hollow cylindrical core carrying printer media to the driveassembly of a printer. FIGS. 5 and 6 show the notch finding mechanism100 according to one embodiment that includes a notch finding spring 101and the support disk 61 having a plurality of support posts 230. Thenotch finding spring 101 includes a plurality of arcuate-shaped fingers102 formed of a flexible sheet material and a base portion 104.

Advantageously, the large number of fingers 102 enables a relativelysmall rotation (e.g., 45°, 30° or less) between the notch finding spring101 and the core of the media supply. For example, the amount ofrotation will generally be the same or less than 360° divided by thenumber of fingers, such as 6, 8 or the illustrated twelve fingers 102.

The fingers 102 have a fixed end 110 and a free end 108, and the fixedends 110 of the fingers 102 are integrally attached to and positionedcircumferentially around the base portion 104 and adjacent to eachother, as shown in FIG. 6. A plurality of spaces 106 are defined betweenthe fingers 102, and the spaces 106 allow the free end 108 of eachfinger 102 to move in a radial direction independently of adjacentfingers 102. Furthermore, the free end 108 of each finger 102 has areduced width w_(f) compared to the portion of the finger 102 adjacentto the free end 108. The width w_(f) of the free end 108 isapproximately matched to the width w_(n) of a notch 22 on the end 23 ofa cylindrical core 20, such as the core 20 shown in FIGS. 2A and 2B,allowing the free end 108 of a finger 102 to seat within the notch 22.

FIG. 7 illustrates the arcuate-profile of one of the fingers 102. Eachfinger 102 extends from its fixed end 110 in a first axial direction andthen bends in a radially outward direction through an arc portion 112and extends towards the free end 108 in a second axial direction, whichis substantially opposite the first axial direction. The portion of thefinger 102 between the arc portion 112 and the free end 108 is biased ina radially outward direction r from an axis of rotation R of the notchfinding spring 101.

As shown in FIGS. 6 and 9, each arc portion 112 has a reduced widthcompared to the portions of the finger 102 adjacent to the arc portion112. The reduced width defines a circular shaped space 120 betweenadjacent fingers 102 that can receive a support post 230. Retaining theincreased width along the remaining portions of the finger 102 providesstrength for the finger 102 and more surface area with which tofrictionally engage the inner diameter 24 of the core 20.

In addition, the diameter of the notch finding spring 101 around the arcportion 112 of the fingers 102 is less than the inner diameter 24 of thecore 20, and the diameter of the notch finding spring 101 around thefree ends 108 of the fingers 102 is greater than the inner diameter 24of the core 20. Because the diameter around the arc portion 112 is lessthan the inner diameter 24 of the core 20, placement of the core 20 overthe notch finding spring 101 is facilitated. And, because the diameterof the notch finding spring 101 around the free ends 108 of the fingers102 is greater than the inner diameter 24 of the core 20, the free ends108 of the fingers 102 are urged against the inner diameter 24 of thecore 20 or into notches 22 that align with the fingers 102. Anillustration of the notch finding spring 101 positioned within thenotched end 23 of the cylindrical core 20 is shown in FIG. 8.

The base portion 104 defines an annular collar 114 that extends in aradially outward direction r from the axis of rotation R of the notchfinding spring 101 to the fixed end 110 of the fingers 102, as shown inFIGS. 6, 7, and 9. The annular collar 114 includes an inner diameterthat approximately matches the outer diameter of the drive shaft 52, ora mounting shaft extending axially from the end of the drive shaft 52,allowing the annular collar 114 to be placed over the end of the driveshaft 52 or mounting shaft. Alternatively, the base portion 104 can besolid (not shown) or define an aperture through the center of the baseportion 104, as shown in FIG. 17B, for receiving a fastener, such as,for example, a screw or bolt, to secure the base portion 104 adjacent tothe end 54 of the drive shaft 52.

One method of manufacturing a notch finding spring 101 includes cuttinginto a flexible sheet of material, such as beryllium copper or full-hard301 stainless steel. The annular collar 114 is cut into the sheet ofmaterial, and the fingers 102 are defined by cutting slots into thematerial that extend from the outer diameter of the annular collar 114to the edge of the sheet of material. The slots are positioned adjacentto each other and circumferentially around the outer diameter of theannular collar 114. After the slots are cut, the portion of each finger102 between the fixed end 110 and the arc portion 112 is bent in a firstaxial direction relative to the axis of rotation R of the notch findingspring 101, the arc portion 112 of each finger 102 is bent in a radiallyoutward direction, and the portion between the arc portion 112 and thefree end 110 is bent in a second axial direction that is substantiallyopposite the first axial direction. When the notch finding spring 101 isfinished, the slots correspond to the spaces 106 defined between thefingers 102.

To bend the fingers 102 into the arcuate-shaped profile, a mandrel, afirst hollow cylinder, and a second hollow cylinder can be utilized. Atleast a portion of the mandrel has an outer diameter that issubstantially the same as the inner diameter of the annular collar 114,and the cut form of the notch finding spring 101 is mounted onto themandrel by engaging the mandrel into the annular collar 114. The firsthollow cylinder has an inner diameter that is approximately the same asthe desired outer diameter of the notch finding spring 101 as measuredaround the portions of each finger 102 intermediate the fixed end 110and the arc portion 112. And, the second hollow cylinder has an innerdiameter approximately the same as the desired outer diameter of thenotch finding spring 101 around the free ends 101. The mandrel ismaneuvered to engage a portion of the cut form into the first hollowcylinder, bending the fixed ends 110 of the fingers 102 in the firstaxial direction. Then, the portions of each finger 102 between the freeend 108 and the arc portion 112 are engaged into the second hollowcylinder, which bends the fingers 102 radially outward and downward inthe second axial direction.

FIGS. 10 through 12 illustrate exemplary dimensional specifications formanufacturing the notch finding spring 101 from a sheet of a berylliumcopper alloy having a yield strength of about 150,000 psi and athickness Q of 0.005 inches. For example, as shown in FIG. 10, the innerdiameter A of the annular collar 114 is approximately 0.185 inches andthe distance B between the center of the annular collar 114 to the fixedend 110 of each finger 102 is approximately 0.135 inches. To define thetwelve fingers 102 shown in FIG. 10, twelve slots corresponding to thetwelve spaces 106 are cut into the material. In addition, the innerradius G of the transition from the fixed end 110 to the portion of thefinger 102 intermediate the fixed end 110 and the arc portion 112 isabout 0.050 inches, the diameter H of the notch finding spring 101around the free ends 108 of the fingers 102 is about 0.558 inches, thediameter J of the notch finding spring 101 around the arc portions 112is approximately 0.465 inches, the diameter W of the notch findingspring 101 around the fixed ends 110 is 0.214 inches, and the radius Kof the portion of the slot that is adjacent the annular collar 114 isabout 0.007 inches. The specifications further show the portion of thefinger 102 extending from the arc portion 112 to the free end 108 ashaving a curvature having an angle L of about 190° and a radius P ofabout 0.4 inches, and the arc portion 112 has an angle M of about 25°and a radius N of about 0.025 inches. In addition, the length Y of thefinger 102 from the arc portion 112 to the free end 108 is about 0.251inches, and the length X that the free end 108 extends below a plane ofthe annular collar 114 is 0.046 inches.

According to FIG. 11, the angle C from the center of one of the fingers102 to the edge of the finger is about 12°, the angle D from the centerof one finger 102 to the center of an adjacent finger 102 is about 42°,and the angle E of each space between the fingers 102 is about 6°. Inaddition, the diameter F of the space 106 between two adjacent arcportions 112 is about 0.055 inches.

FIG. 12 shows another exemplary dimensional specification formanufacturing the arcuate-shaped fingers 102. For example, the innerdiameter A of the annular collar 114 is about 0.125 inches, the radius Gof the transition from the fixed end 110 to the portion of the finger102 intermediate the fixed end 110 and the arc portion 112 is about0.010 inches, the outer radius V of the transition from the fixed end110 to the portion of the finger 102 intermediate the fixed end 110 andthe arc portion 112 is about 0.020 inches, and the arc portion 112 hasan angle M of about 25° and a radius N of about 0.025 inches. Inaddition, the specifications show the portion of the finger 102extending from the arc portion 112 to the free end 108 as having acurvature having an angle L of about 170° and a radius P of about 0.4inches. Furthermore, the flexible sheet material out of which the finger102 is cut is shown as having a thickness Q of approximately 0.010inches. The dimensions described above in relation to FIGS. 10 through12 are exemplary and are one of skill in the art would understand thatvariations are within the scope of the invention.

The notch finding spring 101 is not limited to the specific embodimentdescribed above in relation to FIGS. 4A through 12. For example, in onealternative embodiment, which is shown in FIGS. 14 through 16B, thefingers 102 do not have a reduced width at the free end 108 or a reducedwidth at the arc portion 112. Instead, the width of the fingers 102gradually tapers from the free end 108 towards the arc portion 112, andthe free end 108 has a width that is approximately matched with thewidth of a notch 22 in the core 20. In addition, the spaces 106 betweenthe fingers 102 have a width approximately the same as the diameter ofone of the support posts 230 that extend from the support disk 61. Theexemplary cut detail of a notch finding spring 101 according to thisembodiment is shown in FIGS. 16A and 16B. For example, the angle of eachspace 106 between the fingers 102 is about 6°, and the distance from thecenter of the annular collar 114 to the fixed end 110 outeach finger 102is about 0.1 inches. In another embodiment, which is not shown, thewidth of each finger 102 is uniform along the length of the finger 102.

In addition, another embodiment of the notch finding spring 101, whichis shown in FIGS. 17A and 17B, includes non arcuate-shaped fingers 102.Instead, the fingers 102 extend outwardly and downwardly from the baseportion 104 without bending through an arc portion 112.

As mentioned above, the notch finding mechanism 100 further includes asupport disk 61. According to the embodiment shown in FIGS. 4A through6, the support disk 61 includes a plurality of support posts 230 thatextend in an axial direction from the outer surface 221 of the supportdisk 61. The support posts 230 are positioned circumferentially aroundthe central aperture of the support disk 61. When the annular collar 114of the notch finding spring 101 is positioned over the drive shaft 52and adjacent the support disk 61, each of the spaces 106 between thefingers 102 aligns with and receives one of the support posts 230. Byextending through the each of the spaces 106 between the fingers 102,the support posts 230 prevent the fingers 102 from excessive torsionaldeflection. In another embodiment in which a clutch assembly 60 is notused, the support posts 230 extend axially from the drive disk 55.

In the embodiment shown in FIG. 13, the support disk 61 includes anannular groove 220 on the outer surface 221 of the support disk 61,which is the surface opposite the mounting surface 64. The annulargroove 220 is adapted for seating the free ends 108 of the fingers 102of the notch finding spring 101. By seating the free ends 108 in theannular groove 220, the free ends 108 are prevented from being forced ina radially inward direction past the inner diameter of the annulargroove 220, thereby protecting the fingers 102 from excessive radialdeflection.

Assembly of Notch Finding Mechanism to Drive Assembly The rotationalenergy of the drive motor 51 is transferred to the core 20 by securingthe notch finding spring 101 to the support disk 61 and placing the core20 over the notch finding spring 101. To secure the notch finding spring101 adjacent to the support disk 61 and to hold the support disk 61 infrictional contact with the drive disk 55, one embodiment of the notchfinding mechanism 100 further includes a compression spring 250, awasher 255, and a threaded bolt 256. As shown in FIGS. 5 and 13, thesupport disk 61 and the intermediate frictional disks 201, 202, 203 areplaced over the end 54 of the drive shaft 52 and stacked adjacent thedrive disk 55, as described above in relation to FIG. 5. Then, theannular collar 114 of the notch finding spring 101 is placed over theend 54 of the drive shaft 52 and seated adjacent the support disk 61.

Next, a helical compression spring 250 is placed over the end 54 of thedrive shaft 55 and seated adjacent the annular collar 114 of the notchfinding spring 101. A washer 255 is then placed intermediate the helicalcompression spring 250 and a head portion of a threaded bolt 256, and athreaded portion of the threaded bolt 256 is engaged through the centerof the compression spring 250 and into a threaded aperture 260 thatextends axially from the end 54 of the drive shaft 52 or mounting shafttowards the driven end 53 of the drive shaft 52. When the bolt 256 isfully engaged in the threaded aperture 260, the bolt 256 urges thewasher 255 towards the helical compression spring 250, which forces thecompression spring 250 to push the annular collar 114 of the notchfinding spring 101 into frictional engagement with the support disk 61and the support disk 61 into frictional engagement with the drive disk55 via the intermediate disks 201, 202, 203. FIG. 13 illustrates across-sectional view of the notch finding spring 101 described above inrelation to FIG. 4A engaged into the notched end of the core 20 andcoupled to the drive assembly 50 via the clutch assembly 60 describedabove in relation to FIG. 5.

When the core 20 is placed over the notch finding spring 101, a finger102 may or may not be aligned with a notch 22. If a finger 102 isaligned with a notch 22, the bias of the finger 102 causes it to seatinto the notch 22 automatically. If a finger 102 is not aligned with anotch 22, the drive assembly 50 rotates the notch finding spring 101until a finger 102 aligns with the notch 22. Because a finger 102automatically seats within a notch 22 when the finger 102 is alignedwith the notch 22, the operator does not have to adjust the core 20 oncethe core 20 is placed over the notch finding spring 101.

In another embodiment, which is not shown, the notch finding spring 101is coupled to the drive shaft 52 without a clutch assembly 60. Supportposts 230 extend axially from the drive disk 55 and are positionedcircumferentially around the axis of rotation of the drive shaft 52. Theannular collar 114 of the notch finding spring 101 is placed over theend 53 of the drive shaft 52 and positioned to seat adjacent to thesurface of the drive disk 55 such that the spaces 106 between thefingers 102 are aligned with and receive the support posts 230. The useof a compression spring 250, washer 255, and threaded bolt 256, such asdescribed above in relation to FIG. 13, can be utilized to secure thenotch finding spring 101 into frictional contact with the drive disk 55.

Another embodiment of the invention is a radially biased spring foraxially coupling a drive shaft to a hollow cylindrical shaft. Theradially biased spring includes a base portion and a plurality offingers. Each of the fingers includes a fixed end and a free end, andthe fixed end of each finger is integrally attached to the base portion.The fingers are positioned circumferentially around the base portion soas to define a plurality of spaces between the fingers. The base portionof the radially biased spring is securely mounted to the end of thedrive shaft so that the fixed ends of the fingers are adjacent the endof the drive shaft and the free ends are positioned adjacent the body ofthe drive shaft. When a hollow cylindrical shaft is placed over thefingers, the fingers are biased in a radial outward direction againstthe inside diameter of the cylindrical shaft to couple the drive shaftto the cylindrical shaft.

In an alternative embodiment, shown in FIG. 18, a radially biased springincludes a base portion 104 and a plurality of fingers 302 that extendin an axial direction from the base portion 104 away from the end of thedrive shaft 52 towards a cylindrical shaft 320. The fingers 302 arebiased in a radially outward direction, and each finger 302 includes aprotrusion 303 that extends in a radially outward direction from thefinger 302. The cylindrical shaft 320 includes a driven end 321, andnotches 322 are positioned along an inner diameter of the cylindricalshaft 320 adjacent to the driven end 321. The notches 322 are positionedsuch that they will align with the protrusions 303 on the fingers 302when the fingers 302 are engaged into the cylindrical shaft 320. Theradially outward bias of the fingers 302 urges the protrusions 303 onthe fingers 302 into engagement with the notches 322 in the cylindricalshaft 320, coupling the cylindrical shaft 320 to the drive shaft 52.

The protrusions 303 in the embodiment shown in FIG. 18 are rectangularshaped. However, the protrusions 303 can take on alternative shapes,such as spherical, triangular, or trapezoidal, depending on the shape ofthe notches 322 in the cylindrical shaft 320. For example, in FIG. 19,the protrusions 303 are circular shaped and the notches 322 are dimpleshaped. This embodiment advantageously provides a self-clutchingassembly by allowing the protrusions 303 to disengage the dimple shapednotches 322 when the torque at the end of the drive shaft 52 exceeds apredetermined amount.

In another embodiment, shown in FIG. 20, the protrusions 303 on thefingers 302 extend in a radially inward direction and the fingers 302are biased in a radially inward direction. In addition, the cylindricalshaft 320 includes notches 322 positioned along its outer diameteradjacent to the driven end 321 of the cylindrical shaft 320. To couplethe drive shaft 52 to the driven end 321 of the cylindrical shaft 320,the fingers 302 are engaged into the driven end 321 of the cylindricalshaft 320, and the bias of the fingers 302 urges the protrusions 303 onthe fingers 302 into engagement with the notches 322 on the outerdiameter of the cylindrical shaft 320.

In yet another embodiment, shown in FIG. 21, the fingers 302 are biasedin a radially inward direction, and each finger 302 includes two arcsthat define an S-shape. A first arc 304 is positioned adjacent to thefree end of the finger 302 and is convex relative to the axis ofrotation of the drive shaft 52, and a second arc 305 is positionedadjacent to the first arc 304 and is concave relative to the axis ofrotation of the drive shaft 52. The cylindrical shaft 320 includes atoroidal shaped collar 325 extending in a radially outward directionfrom the outer diameter of the cylindrical shaft 320 adjacent to thedriven end 321 of the cylindrical shaft 320. The collar 325 has adiameter that is greater than the outer diameter of the cylindricalshaft 320 and slightly less than the inner diameter defined by thesecond arcs 305 of the fingers 302. The cylindrical shaft 320 furtherincludes a plurality of notches 322 positioned along the outer diameterof the cylindrical shaft 320 between the toroidal collar 325 and thenon-driven end of the cylindrical shaft 320. To couple the drive shaft52 to the driven end 321 of the cylindrical shaft 320, the fingers 302are engaged over the driven end 321 of the cylindrical shaft 320 and thebias of the fingers 302 urges the second arcs 305 of the fingers 302into engagement with the toroidal collar 325 and the first arcs 304 intoengagement with the notches 322 on the outer diameter of the cylindricalshaft 320. The engagement of the second arcs 305 with the toroidalcollar 325 prevents axial movement of the cylindrical shaft 320 relativeto the drive shaft 52, and the rotational energy from the drive shaft 52is transferred to the cylindrical shaft 320 through the engagement ofthe first arcs 304 into the notches 322 adjacent to the toroidal collar325.

FIG. 22 shows a variation of the embodiment described in relation inFIG. 21 wherein the cylindrical shaft 320 has a toroidal collar 325 thatextends from the outer diameter of the cylindrical shaft 320 in aradially outward direction, and the notches 322 are positioned along acrest 326 of the toroidal collar 325 on the inner diameter of thecylindrical shaft 320. The fingers 302 include at least one arc 306 thatis concave relative to the axis of rotation of the drive shaft 52, andupon engaging the fingers 302 into the cylindrical shaft 320, the arcs306 on the fingers 302 engage into the toroidal collar 325 and thenotches 322 therein. The engagement of the arcs 306 with the toroidalcollar 325 prevents axial movement of the cylindrical shaft 320 relativeto the drive shaft 52, and the rotational energy from the drive shaft 52is transferred to the cylindrical shaft 320 through the engagement ofthe arcs 306 into the notches 322 on the toroidal collar 325.

In yet another alternative embodiment, fingers 302 extend axially fromthe circumference of a cylinder 310 having a threaded exterior portion311, as shown in FIG. 23. The threaded exterior portion 311 engages athreaded inner diameter 340 of a drive shaft 52. The fingers 302 includeprotrusions 303 that extend in a radially inward direction, and theseprotrusions 303 engage notches 322 positioned within a trough of anannular collar 330 that extends in a radially inward direction from theouter diameter of the cylindrical shaft 320 when the fingers 302 areengaged over the cylindrical shaft 320. If the torque on the drive shaft52 exceeds a particular amount at the end of the drive shaft 52, theprotrusions 303 on the fingers 302 disengage from the notches 322 or thethreaded portion 311 of the cylinder 310 disengages from the threadedinner diameter 340 of the drive shaft 52.

FIG. 24 illustrates another embodiment in which the end of the driveshaft 52 includes a first face 345 that includes a plurality ofprotrusions 341 extending from the first face 345 in an axial directionaway from the drive shaft 52. The cylindrical shaft 320 includes adriven end 321 that has a second face 350, and the second face 350 ofthe driven end 321 includes a plurality of notches 352 that align withthe protrusions 341 on the drive shaft 52 and are configured forreceiving the protrusions 341 when the driven end 321 of the cylindricalshaft 320 and the end of the drive shaft 52 are place adjacent to eachother. When the protrusions 341 of the drive shaft 52 are engaged intothe notches 352 on the cylindrical shaft 320, the rotational energy ofthe drive shaft 52 can be transferred to the cylindrical shaft 320. Inaddition, a plurality of fingers 302 extend from the end of the driveshaft 52 in an axial direction towards a cylindrical shaft 320. Toprevent the axial movement of the cylindrical shaft 320 relative to thedrive shaft 52, the fingers 302 further include a protrusion 303 thatextends in a radially inward direction, and the protrusion 303 engages agroove 330 in the outer diameter of the cylindrical shaft 320.

FIGS. 25 through 28 illustrate exemplary alternative embodiments offinger shapes. For example, FIGS. 25 and 26 illustrate fingers 302 thathave a free end 108, a fixed end 110, and an elongated body extendingbetween the free end 108 and the fixed end 110. A protrusion 303 extendsfrom the elongated body between the fixed end 110 of the finger 302 anda middle portion of the elongated body. The protrusion 303 may extend ina radially inward direction as shown in FIG. 25 or in a radially outwarddirection as shown in FIG. 26.

FIG. 27 illustrates another embodiment of a finger 302 that has a freeend 108, a fixed end 110, and an elongated body extending between thefree end 108 and the fixed end 110. A protrusion 303 extends from amiddle portion of the elongated body, and the free end 108 of the finger302 defines a hook shape. The hook-shaped free end 108 can bend radiallyinward or radially outward to facilitate the insertion of the finger 302into the inner diameter of the cylindrical shaft or onto the outerdiameter of the cylindrical shaft, respectively.

FIG. 28 illustrates a finger 302 having a fixed end 110, a free end 108,and a U-shaped body that extends between the free end 108 and the fixedend 110 and includes an arcuate portion 401. The finger 302 extends froma base portion 104 in a first axial direction, bends in a radiallyoutward direction through the arc portion 401, and extends in a secondaxial direction to the free end 108, wherein the first axial directionis substantially opposite the second axial direction. In addition, thefinger 302 includes a protrusion 303 that extends in a radially outwarddirection and is positioned between the arc portion 401 and the free end108 of the finger 302. The finger 302 is suited for engaging notcheslocated along the inner diameter of a cylindrical shaft. In analternative embodiment, which is not shown, the finger extends from thebase portion in the first axial direction, but bends in a radiallyinward direction through the arc portion before extending in the secondaxial direction to the free end. The finger also includes a protrusionpositioned between the arc portion and the free end of the finger, butunlike the finger shown in FIG. 28, the protrusion extends in a radiallyinward direction. This finger is adapted for engaging notches locatedalong the outer diameter of the cylindrical shaft.

In other alternative embodiments, the fingers 302 described above arepositioned on the driven end 321 of the cylindrical shaft 320, and thestructure for engaging the fingers 302 is positioned on the drive end ofthe drive shaft 52. For example, as shown in FIG. 29, fingers 302 extendfrom the driven end 321 of the cylindrical shaft 320 towards the driveshaft 52. The drive shaft 52 includes a hollow cylindrical portion atthe drive end that includes a plurality of notches 441. The fingers 302,which are biased in a radially outward direction, engage the notches 441and transfer rotational energy from the drive shaft 52 to thecylindrical shaft 320.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended concepts.Although specific terms are employed herein, they are used in a genericand descriptive sense only and not for purposes of limitation.

1. A notch finding mechanism for at least partially supporting anddriving a core of a printer media supply, said core defining at leastone notch at an end of the core, the notch finding mechanism comprising:a drive shaft; and a notch finding spring driven by the drive shaft,said notch finding spring comprising: a plurality of fingers positionedcircumferentially about a central axis and adjacent to each other; eachof said fingers being biased in a radially outward direction; each ofsaid fingers having a free end; wherein the bias of one of the fingersurges the free end of said finger into the notch defined in the end ofthe core when the core is placed over the plurality of fingers androtated.
 2. A notch finding mechanism of claim 1, wherein each of theplurality of fingers is constructed of a flexible sheet material.
 3. Anotch finding mechanism of claim 2, wherein the fingers define aplurality of spaces therebetween.
 4. A notch finding mechanism of claim3, wherein said free end of each of the fingers has a widthapproximately matched to a width of the notch defined at the end of thesupply core.
 5. A notch finding mechanism of claim 4, further comprisinga support disk supporting the plurality of fingers.
 6. A notch findingmechanism of claim 5, further comprising a plurality of support postsextending in the axial direction from a surface of the support disk,each of said plurality of support posts extending into a respective oneof said plurality of spaces defined between said fingers.
 7. A notchfinding mechanism of claim 6, further comprising a frictional clutchpositioned between the support disk and a drive disk connected to thedrive shaft.
 8. A method of supporting and driving a core of a printermedia supply, the method comprising: positioning the core over a notchfinding spring having a plurality of fingers with a radially outwardbias; and rotating the core and the notch finding spring relative toeach other a small amount until one of the fingers biases into a notchdefined in the core.
 9. A method of claim 8, wherein the small amount is30° or less.
 10. A notch finding spring for driving a core, said coredefining at least one notch adjacent to an end of the core, the notchfinding spring comprising: a plurality of fingers; said fingerspositioned circumferentially about a central axis and adjacent to eachother; each of said fingers being biased in a radial direction; each ofsaid fingers having a free end, said free end comprising an engagingportion; wherein the bias of one of the fingers urges the engagingportion into the notch when the core is placed adjacent to the pluralityof fingers and rotated.
 11. A notch finding spring of claim 10 whereinthe fingers are biased in a radially inward direction.
 12. A notchfinding spring of claim 10 wherein the engaging portion is at an end ofthe free end of each finger.
 13. A notch finding spring of claim 10wherein the engaging portion is adjacent an end of the free end of eachfinger.
 14. A notch finding spring of claim 10 wherein the engagingportion is a protrusion extending in a radial direction from eachfinger, said protrusion adapted for engaging the notch in the core. 15.A notch finding spring of claim 10 wherein the engaging portioncomprises a first arcuate shape having a first diameter and the notchcomprises a second arcuate shape having a second diameter, the firstdiameter being slightly smaller than the second diameter, and whereinthe engaging portion is adapted to disengage the notch when a torque atthe engaging portion exceeds a predetermined amount.
 16. A notch findingspring of claim 10 wherein the fingers are biased in a radially outwarddirection.
 17. A notch finding spring of claim 16, wherein each of theplurality of fingers is constructed of a flexible sheet material.
 18. Anotch finding spring of claim 17, wherein each of the plurality offingers extends from a fixed end in a first axial direction.
 19. A notchfinding spring of claim 18, wherein each of said fingers has anarcuate-shaped profile, said arcuate-shaped profile defined by each ofsaid fingers extending in the first direction from the fixed end andbending in a radially outward direction through an arc portion to extendin a second axial direction generally opposite the first axial directionand toward said free end.
 20. A notch finding spring of claim 19,wherein the fingers define a plurality of spaces therebetween.
 21. Anotch finding spring of claim 20, wherein said free end of each of thefingers has a width approximately matched to a width of the notchdefined at the end of the supply core.
 22. A notch finding spring ofclaim 21, wherein a first diameter around the free ends of the pluralityof fingers is greater than an inside diameter of the supply core and asecond diameter around the arc portions of the plurality of fingers isless than the inside diameter of the supply core.
 23. A notch findingspring of claim 22, wherein each of said fingers includes a middleportion between said arc portion and said free end, said middle portionhaving a width greater than a width of said free end.
 24. A notchfinding spring of claim 23, wherein said arc portion of each of saidfingers has a reduced cross section.
 25. A notch finding spring of claim24, wherein said plurality of spaces at locations between the arcportions are adapted for aligning with and receiving a plurality ofrigid support posts.
 26. A notch finding spring for driving a core, saidnotch finding spring being secured to the core, the notch finding springcomprising: a plurality of fingers; said fingers positionedcircumferentially about a central axis and adjacent to each other; eachof said fingers being biased in a radial direction; each of said fingershaving a free end, said free end comprising an engaging portion; whereinthe bias of one of the fingers urges the engaging portion into a notchdefined adjacent to an end of a drive shaft when the drive shaft isplaced adjacent to the plurality of fingers and relatively rotated asmall amount.